Designs of Masks in Thickness Uniformity

A method of a static mask design in thickness uniformity is fully described and analyzed by simulations of the film thickness theory, based on the assumption that atoms and molecules emitted by the source travel in straight lines to the substrates, which rotate about the central axis during films deposition. The design method can be practically used for all optical coatings produced by vacuum deposition. The solution of a mask shape is unique for a stationary set of coating parameters. A set of coating parameters include the height of the apex of the dome above the source, the curvature radius of the dome, the distance from the source to the rotation axis of the dome, the emissive characteristics of the source which modify the cosine law of the surface source, the form and area of the source. The influence of coating parameters on shapes of masks is also investigated in this study. The mask obtained by the design is a good initial profile in thickness uniformity during vacuum deposition.